The present invention relates to a motor drive device and a motor drive integrated circuit device, and to a technique effective when applied to a rotational control technique of a three-phase spindle motor for HDD (Hard Disk Driver) or the like, for example.
PWM (Pulse Width Modulation) driving has heretofore been adopted in a system for driving a spindle motor for an HDD device. In the case of the PWM driving, power consumed or used up by a transistor to be driven can greatly be reduced. However, there may be cases where noise occurs since an output voltage is transitioned between a power supply and GND at high speed, and an error rate of the HDD device is degraded. When a switching time is made slow to avoid it, a switching loss increases so that power is increased. Thus, a suitable time having taken into consideration the noise and switching loss is required as the switching time for a spindle. Incidentally, Japanese Unexamined Patent Publication No. Hei 11(1999)-69872 has been disclosed as a document related to the noise of the HDD device. A technique described in such a publication relates to a reduction in noise produced from a VCM driver that performs positional control of a magnetic head. Ones related to the noise produced upon driving of the spindle motor have not been disclosed.